The present invention relates to a device for securing a tubular member, in particular a motor vehicle steering column, which can be adjusted by pivoting and/or by axial displacement.
Increasing importance is being attached to a driver of a motor vehicle being able to adjust the position of the steering wheel, this contributing not only to the comfort of the driver but also to the ease of handling of the vehicle. Consequently, the steering column which supports the steering wheel is mounted pivotably on a preferably horizontal fixed shaft and/or is made in several elements capable of being displaced telescopically relative to one another. It is furthermore supported at an intermediate point by a securing device which comprises a fitting, fixed onto the bodywork and forming an inverted-U-shaped structure in which the column can be displaced, an assembly member integral with the column and in contact by opposite faces with the side walls of the U of the fitting, and means for locking by bringing the side walls of the fitting closer together, comprising a tie bolt which traverses, parallel to the pivot axis, the side faces of the fitting in curved slots between two outer bearing stops.
Various types of clamping means have been proposed and used hitherto in order to act on the side walls of the fitting via the tie bolt. In certain cases, they are very simple in construction; they comprise, for example, a nut screwed onto a screw thread of the end of the tie bolt, but their efficiency is unreliable since the action exerted on the nut can vary from one driver to another.
Other more complex devices make use of cams or toggle-joint systems driven by a control lever which can move in a plane perpendicular to the axis of the steering column. The clamping is more accurate but these devices are subject to wear and to damage under the influence, in particular, of external attack such as corrosion, impacts etc., with the result that it is necessary to check them and adjust them frequently. Furthermore, the control lever is often an inconvenience to the driver.